This invention relates to multi-purpose electrical test jacks and, more particuarly, to such test jacks which include a partially threaded, terminal pin and a spring clamp, connected to a tubular receptacle adapted first to removably receive the pin therein by axial insertion and for greater security of the connection by optionally screw-fitting together the partially threaded pin and receptacle.
Various types of electrical connectors have been developed in the past, such as Heckman U.S. Pat. No. 1,761,728 which shows a fully threaded pin and receptacle connector. This is a very secure but cumbersome type of connection where the pin must be fully screwed into or unscrewed from the receptacle. A less cumbersome but also secure connection is shown in Jackson U.S. Pat. No. 2,375,656 where a pin may be longitudinally inserted into a sleeve or housing and snapped together. The drawback to this type of connector is that once the connection is made, it cannot simply be unsnapped and pulled apart, but a locking element 58 must first be uncoupled. A more recent development is the "plug in" jack type of electrical connector which may be both connected and disconnected by simply longitudinally inserting the pin into or removing the pin from the sleeve or housing, such as shown in Bohl et al U.S. Pat. No. 4,736,480 ; Sihn British Pat. No. 708,468 and Paufler French Pat. No. 876,663. While it is generally desirable, when working with electrical test equipment, to have a quick and easy connection, as these patents show, it is also important to have a more secure connection. But, none of these patents show an effective means for securing the "plug in" connection so that it will not readily pull apart in normal usage.
Accordingly, it is the principal object of this invention to provide a multi-purpose jack assembly with a "plug-in" terminal pin that can simply be axially inserted into a receptacle connected to a clamping device for making quick electrical connections and in which the "plug-in" connection may optionally be secured by screw-fitting the axially coupled parts together.